🧱 Ductile Iron Pipe Sizes and Pressure Classes Explained
- Pipekom
- Jul 29
- 2 min read
Ductile iron (DI) pipes are the backbone of water transmission and distribution networks worldwide. For engineers, contractors, and procurement professionals, understanding the sizing and pressure class system — especially PN ratings — is essential for selecting the right pipe for a given project.
🔍 What Are PN Ratings in Ductile Iron Pipes?
PN stands for "Pressure Nominal" — a classification used to define the maximum internal pressure (in bars) that a pipe can withstand at 20°C over a long period.
Common PN ratings for DI pipes include:
PN Rating | Pressure (bar) | Pressure (psi) | Common Usage |
PN 10 | 10 bar | 145 psi | Gravity-fed or low-pressure systems |
PN 16 | 16 bar | 232 psi | Most common for water supply |
PN 25 | 25 bar | 362 psi | High-pressure zones, industrial |
PN 40 | 40 bar | 580 psi | Specialized, high-demand cases |
📏 Standard Sizes of Ductile Iron Pipes
Ductile iron pipes are produced in a wide range of nominal diameters, typically from DN 80 mm to DN 2000 mm. However, the most common sizes used in municipal and infrastructure projects range between:
DN 100 – DN 600 mm: Residential and small urban projects
DN 700 – DN 1200 mm: Major transmission mains
DN 1400+ mm: Mega infrastructure (e.g., national water grids, desalination output)
🛠️ Mechanical Strength and Durability
DI pipes offer:
High tensile strength (>420 MPa)
Excellent impact resistance
Ability to handle internal pressure surges
Long service life (50–100 years depending on conditions)
Combined with their coatings and linings (zinc, bitumen, epoxy), ductile iron pipes outperform plastic or steel in corrosion resistance in many water transmission environments.
🌍 Where Are PN Ratings Most Relevant?
In regions with fluctuating water pressures, elevation changes, or high demand cycles — such as:
Middle East (e.g., UAE, Saudi Arabia): Urban water supply + agriculture
Africa: Water transmission from remote boreholes or treatment plants
Asia: Municipal upgrades with tight design specs
📦 Pipekom and DI Pipe Sizing Expertise
At Pipekom, we help clients:
Select the right size and PN class
Optimize for cost vs. pressure requirements
Ensure full compliance with local water authority specs (DEWA, Ashghal, NWC, etc.)
Whether it’s 400mm PN16 pipes for Jordan or DN 1000 PN25 for Saudi Arabia, we source and deliver the best-fit solution — fast.
